E-Print Archive

There are 3813 abstracts currently viewable.


Search:

Advanced Search
Options
Main Page Add New E-Print Submitter
Information
Feedback
News Help/FAQ About Preferences
Manage Key Phrase
Notification
Magnetohydrodynamics modeling of coronal magnetic field and solar eruptions based on the photospheric magnetic field  

Satoshi Inoue   Submitted: 2016-07-04 19:28

In this paper, we summarize current progress on using the observed magnetic fields for magnetohydrodynamics (MHD) modeling of the coronal magnetic field and of solar eruptions, including solar flares and coronal mass ejections (CMEs). Unfortunately, even with the existing state-of-the-art solar physics satellites, only the photospheric magnetic field can be measured. We first review the 3D extrapolation of the coronal magnetic fields from measurements of the photospheric field. Specifically, we focus on the nonlinear force-free field (NLFFF) approximation extrapolated from the three components of the photospheric magnetic field. On the other hand, because in the force-free approximation the NLFFF is reconstructed for equilibrium states, the onset and dynamics of solar flares and CMEs cannot be obtained from these calculations. Recently, MHD simulations using the NLFFF as an initial condition have been proposed for understanding these dynamics in a more realistic scenario. These results have begun to reveal complex dynamics, some of which have not been inferred from previous simulations of hypothetical situations, and they have also successfully reproduced some observed phenomena. Although MHD simulations play a vital role in explaining a number of observed phenomena, there still remains much to be understood. Herein, we review the results obtained by state-of-the-art MHD modeling combined with the NLFFF.

Authors: Satoshi Inoue
Projects: None

Publication Status: Published
Last Modified: 2016-07-06 10:36
Go to main E-Print page  Edit Entry  Download Preprint  Delete Entry 

Structure and Stability of Magnetic Fields in Solar Active Region 12192 Based on Nonlinear Force-Free Field Modeling  

Satoshi Inoue   Submitted: 2016-02-22 03:54

We analyze a three-dimensional (3D) magnetic structure and its stability in large solar active region(AR) 12192, using the 3D coronal magnetic field constructed under a nonlinear force-free field (NLFFF) approximation. In particular, we focus on the magnetic structure that produced an X3.1-class flare which is one of the X-class flares observed in AR 12192. According to our analysis, the AR contains multiple-flux-tube system, e.g., a large flux tube, both of whose footpoints are anchored to the large bipole field, under which other tubes exist close to a polarity inversion line (PIL). These various flux tubes of different sizes and shapes coexist there. In particular, the later are embedded along the PIL, which produces a favorable shape for the tether-cutting reconnection and is related to the X-class solar flare. We further found that most of magnetic twists are not released even after the flare, which is consistent with the fact that no observational evidence for major eruptions was found. On the other hand, the upper part of the flux tube is beyond a critical decay index, essential for the excitation of torus instability before the flare, even though no coronal mass ejections (CMEs) were observed. We discuss the stability of the complicated flux tube system and suggest the reason for the existence of the stable flux tube. In addition, we further point out a possibility for tracing the shape of flare ribbons, on the basis of a detailed structural analysis of the NLFFF before a flare.

Authors: S. Inoue, K. Hayashi, & K. Kusano
Projects: None

Publication Status: The Astrophysical Journal,Volume 818, Number 2
Last Modified: 2016-02-22 20:42
Go to main E-Print page  Edit Entry  Download Preprint  Delete Entry 

Magnetohydrodynamic Simulation of the X2.2 Solar Flare on 2011 February 15. I. Comparison with the Observations  

Satoshi Inoue   Submitted: 2014-06-06 12:50

We performed a magnetohydrodynamic (MHD) simulation using a nonlinear force-free field (NLFFF) in solar active region 11158 to clarify the dynamics of an X2.2-class solar flare. We found that the NLFFF never shows the dramatic dynamics seen in observations, i.e., it is in a stable state against the perturbations. On the other hand, the MHD simulation shows that when the strongly twisted lines are formed at close to the neutral line, which are produced via tether-cutting reconnection in the twisted lines of the NLFFF, they consequently erupt away from the solar surface via the complicated reconnection. This result supports the argument that the strongly twisted lines formed in NLFFF via tether-cutting reconnection are responsible for breaking the force balance condition of the magnetic fields in the lower solar corona. In addition to this, the dynamical evolution of these field lines reveals that at the initial stage the spatial pattern of the footpoints caused by the reconnection of the twisted lines appropriately maps the distribution of the observed two-ribbon flares. Interestingly, after the flare, the reconnected field lines convert into a structure like the post-flare loops, which is analogous to the extreme ultraviolet image taken by the Solar Dynamics Observatory. Eventually, we found that the twisted lines exceed a critical height at which the flux tube becomes unstable to the torus instability. These results illustrate the reliability of our simulation and also provide an important relationship between flare and coronal mass ejection dynamics.

Authors: S. Inoue, K. Hayashi, T. Magara, G. S. Choe, and Y. D. Park
Projects: None

Publication Status: published
Last Modified: 2014-06-09 06:57
Go to main E-Print page  Edit Entry  Download Preprint  Delete Entry 

Nonlinear Force-Free Extrapolation of the Coronal Magnetic Field Based on the MHD Relaxation Method  

Satoshi Inoue   Submitted: 2013-11-15 05:44

We develop a nonlinear force-free field (NLFFF) extrapolation code based on the magnetohydrodynamic (MHD) relaxation method. We extend the classical MHD relaxation method in two important ways. First, we introduce an algorithm initially proposed by ?cite{2002JCoPh.175..645D} to effectively clean the numerical errors associated with "nabla"cdot?vec{B}. Second, the multi-grid type method is implemented in our NLFFF to perform direct analysis of the high-resolution magnetogram data. As a result of these two implementations, we successfully extrapolated the high resolution force-free field introduced by ?cite{1990ApJ...352..343L} with better accuracy in a drastically shorter time. We also applied our extrapolation method to the MHD solution obtained from the flux-emergence simulation by ?cite{2012ApJ...748...53M}. We found that NLFFF extrapolation may be less effective for reproducing areas higher than a half-domain, where some magnetic loops are found in a state of continuous upward expansion. However, an inverse S shaped structure consisting of the sheared and twisted loops formed in the lower region can be captured well through our NLFFF extrapolation method. We further discuss how well these sheared and twisted fields are reconstructed by estimating the magnetic topology and twist quantitatively.

Authors: S. Inoue, T. Magara, V. S. Pandey, D. Shiota, K. Kusano, G. S. Choe and K. S. Kim
Projects: None

Publication Status: Accepted for publication in The Astrophysical Journal
Last Modified: 2013-11-17 13:29
Go to main E-Print page  Edit Entry  Download Preprint  Delete Entry 


Key
Go to main E-Print pageGo to main E-Print page.
Download PreprintDownload Preprint.
Submitter's HomepageSubmitters Homepage.
Edit EntryEdit Entry.
Delete AbstractDelete abstract.

Abstracts by Author
Magnetohydrodynamics modeling of coronal magnetic field and solar eruptions based on the photospheric magnetic field
Structure and Stability of Magnetic Fields in Solar Active Region 12192 Based on Nonlinear Force-Free Field Modeling
Magnetohydrodynamic Simulation of the X2.2 Solar Flare on 2011 February 15. I. Comparison with the Observations
Nonlinear Force-Free Extrapolation of the Coronal Magnetic Field Based on the MHD Relaxation Method

Related Pages
MSU Solar Physics.
Max Millennium Science Mail Archive.
Max Millennium Message of the Day Mail Archive.
Max Millennium Flare Catalog

Archive Maintainer
Alisdair Davey



© 2003 Solar Physics Group - Montana State University